Alsaloop: sync mode PLAYSHIFT + Loopback on playback side
Pavel Hofman
pavel.hofman at ivitera.com
Mon Oct 4 16:32:45 CEST 2021
Dne 04. 10. 21 v 13:55 Jaroslav Kysela napsal(a):
>>> Hi,
>>>
>>> I would not touch the controls associated to the capture PCM by default.
>>> It would be possible to add another alsaloop option and code to
>>> configure the rate shift control identifier separately for this use
>>> case. The user should avoid the double pitch control (playback +
>>> capture) for the loopback devices.
>>
>> Thanks for your input. I am not sure I understand correctly your
>> intention.
>>
>> The current code already avoids running playback and capture pitch
>> control concurrently by one alsaloop as the loop->sync is either
>> SYNC_TYPE_CAPTRATESHIFT or SYNC_TYPE_PLAYRATESHIFT. IMO the current code
>> ignores SYNC_TYPE_PLAYRATESHIFT because the code jumps to
>> set_rate_shift(loop->play, pitch)
>> https://github.com/alsa-project/alsa-utils/blob/master/alsaloop/pcmjob.c#L1103
>>
>> but the lhandle->ctl_rate_shift elem is never set for playback side in
>> pcmjob.c:openctl
>> https://github.com/alsa-project/alsa-utils/blob/master/alsaloop/pcmjob.c#L1208
>>
>> (lhandle->loopback->play == lhandle). I confirmed it using the debug
>> patch you accepted today (thanks! :-)).
>>
>> Therefore my patch of the openctl moves the "PCM Notify" and "PCM Rate
>> Shift 100000" setup before the playback check, so that lhandles of both
>> directions can have the two elems configured.
>>
>> But the loopback->play lhandle should configure elements for the capture
>> side of the snd-aloop pipe which I do not know how to locate nicely. I
>> can always use some hack "if device==0 then use device = 1" for the
>> playback side etc. but that does not look nice.
>
> Please, assume that the 'PCM Rate Shift 100000' control is for the
> capture PCM only by default. The applications should not handle those
> driver specific mapping.
>
> If the user wants to use this control for the playback side, a new
> command line option may be added to cope with the alternate playback
> rate shift control indentifier (it may be parsed using
> snd_ctl_ascii_elem_id_parse() for example). So the user may specify the
> correct (different) device number there.
Thanks, please can you comment on this patch? alsaloop.1 not updated
yet. Tested to work OK, while checking via amixer that the elem 'PCM
Rate Shift 100000',device=1 gets controlled:
pavel at precision:~/work/rpi-gadget/alsa-utils/alsaloop$ ./alsaloop -vv -l
10000 v -c 2 -r 48000 -f S32_LE -C hw:Quartet -P hw:Loopback -S
playshift -x iface=PCM,name='PCM Rate Shift 100000',device=1
!!!Scheduler set to Round Robin with priority 99 FAILED!
Opened PCM element 'iface=PCM,name=PCM Rate Shift 100000,device=1' for
playback rate adjust of hw:10
Hardware PCM card 10 'Loopback' device 0 subdevice 0
Its setup is:
stream : PLAYBACK
access : RW_INTERLEAVED
format : S32_LE
subformat : STD
channels : 2
rate : 48000
exact rate : 48000 (48000/1)
msbits : 32
buffer_size : 39992
period_size : 4999
period_time : 104145
tstamp_mode : NONE
tstamp_type : MONOTONIC
period_step : 1
avail_min : 32494
period_event : 0
start_threshold : 2147483647
stop_threshold : 39992
silence_threshold: 0
silence_size : 0
boundary : 5628373634306277376
appl_ptr : 0
hw_ptr : 0
Hardware PCM card 0 'Infrasonic Quartet' device 0 subdevice 0
Its setup is:
stream : CAPTURE
access : RW_INTERLEAVED
format : S32_LE
subformat : STD
channels : 2
rate : 48000
exact rate : 48000 (48000/1)
msbits : 24
buffer_size : 32768
period_size : 4096
period_time : 85333
tstamp_mode : NONE
tstamp_type : MONOTONIC
period_step : 1
avail_min : 4096
period_event : 0
start_threshold : 2147483647
stop_threshold : 32768
silence_threshold: 0
silence_size : 0
boundary : 4611686018427387904
appl_ptr : 0
hw_ptr : 0
Latency 9999 frames, 208312.500us, 208.312500ms (4.8005Hz)
shared buffer!!!
playback hw:Loopback/capture hw:Quartet sync type: PLAYRATESHIFT
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000
(min/max samples = 0/0)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = 0/35)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = 0/35)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = 0/35)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = 0/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = 0/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = 0/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = -14/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000
(min/max samples = -29/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00003125
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = -32/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000
(min/max samples = -38/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 0.99998958
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = -41/39)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = -41/39)
Without specifying the -x CONTROL_NAME param (no rate control applied)
the pitch starts diverging:
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00000000
(min/max samples = 0/0)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00001042
(min/max samples = 0/14)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00002083
(min/max samples = 0/16)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00003125
(min/max samples = 0/17)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00004167
(min/max samples = 0/21)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00005208
(min/max samples = 0/23)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00006250
(min/max samples = 0/27)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00007292
(min/max samples = 0/29)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00008333
(min/max samples = 0/33)
New pitch for playback hw:Loopback/capture hw:Quartet: 1.00009375
(min/max samples = 0/34)
Thanks a lot,
Pavel.
=============================================================
diff --git a/alsaloop/alsaloop.c b/alsaloop/alsaloop.c
index 06ffadf..4358db0 100644
--- a/alsaloop/alsaloop.c
+++ b/alsaloop/alsaloop.c
@@ -175,6 +175,7 @@ void help(void)
"-C,--cdevice capture device\n"
"-X,--pctl playback ctl device\n"
"-Y,--cctl capture ctl device\n"
+"-x,--prateshift playback 'PCM Rate Shift 100000' ascii ctl name\n"
"-l,--latency requested latency in frames\n"
"-t,--tlatency requested latency in usec (1/1000000sec)\n"
"-f,--format sample format\n"
@@ -362,6 +363,7 @@ static int parse_config(int argc, char *argv[],
snd_output_t *output,
{"cdevice", 1, NULL, 'C'},
{"pctl", 1, NULL, 'X'},
{"cctl", 1, NULL, 'Y'},
+ {"prateshift", 1, NULL, 'x'},
{"latency", 1, NULL, 'l'},
{"tlatency", 1, NULL, 't'},
{"format", 1, NULL, 'f'},
@@ -391,6 +393,7 @@ static int parse_config(int argc, char *argv[],
snd_output_t *output,
char *arg_cdevice = NULL;
char *arg_pctl = NULL;
char *arg_cctl = NULL;
+ char *arg_prateshift = NULL;
unsigned int arg_latency_req = 0;
unsigned int arg_latency_reqtime = 10000;
snd_pcm_format_t arg_format = SND_PCM_FORMAT_S16_LE;
@@ -420,7 +423,7 @@ static int parse_config(int argc, char *argv[],
snd_output_t *output,
while (1) {
int c;
if ((c = getopt_long(argc, argv,
- "hdg:P:C:X:Y:l:t:F:f:c:r:s:benvA:S:a:m:T:O:w:UW:z",
+ "hdg:P:C:X:Y:x:l:t:F:f:c:r:s:benvA:S:a:m:T:O:w:UW:z",
long_option, NULL)) < 0)
break;
switch (c) {
@@ -446,6 +449,9 @@ static int parse_config(int argc, char *argv[],
snd_output_t *output,
case 'Y':
arg_cctl = strdup(optarg);
break;
+ case 'x':
+ arg_prateshift = strdup(optarg);
+ break;
case 'l':
err = atoi(optarg);
arg_latency_req = err >= 4 ? err : 4;
@@ -627,6 +633,10 @@ static int parse_config(int argc, char *argv[],
snd_output_t *output,
logit(LOG_CRIT, "Unable to add ossmixer controls.\n");
exit(EXIT_FAILURE);
}
+ if (arg_prateshift) {
+ play->prateshift_name = arg_prateshift;
+ }
+
#ifdef USE_SAMPLERATE
loop->src_enable = arg_samplerate > 0;
if (loop->src_enable)
diff --git a/alsaloop/alsaloop.h b/alsaloop/alsaloop.h
index 1dbcefe..7a98ef3 100644
--- a/alsaloop/alsaloop.h
+++ b/alsaloop/alsaloop.h
@@ -127,6 +127,7 @@ struct loopback_handle {
snd_ctl_elem_value_t *ctl_format;
snd_ctl_elem_value_t *ctl_rate;
snd_ctl_elem_value_t *ctl_channels;
+ char *prateshift_name; /* ascii name for the playback rate shift ctl
elem */
};
struct loopback {
diff --git a/alsaloop/pcmjob.c b/alsaloop/pcmjob.c
index 845ab82..a4b28e3 100644
--- a/alsaloop/pcmjob.c
+++ b/alsaloop/pcmjob.c
@@ -1101,7 +1101,8 @@ void update_pitch(struct loopback *loop)
#endif
}
else if (loop->sync == SYNC_TYPE_PLAYRATESHIFT) {
- set_rate_shift(loop->play, pitch);
+ // pitch is capture-based, playback side requires reciprocal
+ set_rate_shift(loop->play, 1 / pitch);
#ifdef USE_SAMPLERATE
if (loop->use_samplerate) {
loop->src_data.src_ratio =
@@ -1200,16 +1201,66 @@ static void openctl_elem(struct loopback_handle
*lhandle,
}
}
+static int openctl_play_rateshift(struct loopback_handle *lhandle,
+ char *ascii_name) {
+ int err;
+ snd_ctl_elem_id_t *id;
+ snd_ctl_elem_value_t **elem;
+
+ elem = &lhandle->ctl_rate_shift;
+
+ if (snd_ctl_elem_value_malloc(elem) < 0) {
+ return -ENOMEM;
+ }
+
+ if (snd_ctl_elem_id_malloc(&id)) {
+ snd_ctl_elem_value_free(*elem);
+ return -ENOMEM;
+ }
+
+ if (snd_ctl_ascii_elem_id_parse(id, ascii_name)) {
+ snd_ctl_elem_id_free(id);
+ snd_ctl_elem_value_free(*elem);
+ fprintf(stderr, "Wrong control identifier: %s\n", ascii_name);
+ return -EINVAL;
+ }
+
+ snd_ctl_elem_value_set_id(*elem, id);
+ err = snd_ctl_elem_read(lhandle->ctl, *elem);
+ if (err < 0) {
+ snd_ctl_elem_id_free(id);
+ snd_ctl_elem_value_free(*elem);
+ return err;
+ } else {
+ snd_output_printf(lhandle->loopback->output,
+ "Opened PCM element '%s' for playback rate adjust of %s\n",
+ ascii_name, snd_ctl_name(lhandle->ctl));
+ }
+ return 0;
+}
+
+
static int openctl(struct loopback_handle *lhandle, int device, int
subdevice)
{
int err;
- lhandle->ctl_rate_shift = NULL;
if (lhandle->loopback->play == lhandle) {
+ // play only
+ if (lhandle->prateshift_name) {
+ err = openctl_play_rateshift(lhandle, lhandle->prateshift_name);
+ if (err < 0) {
+ logit(LOG_CRIT, "Unable to open playback PCM Rate Shift elem '%s'.\n",
+ lhandle->prateshift_name);
+ exit(EXIT_FAILURE);
+ }
+ }
+
if (lhandle->loopback->controls)
goto __events;
return 0;
}
+ // capture only
+ lhandle->ctl_rate_shift = NULL;
openctl_elem(lhandle, device, subdevice, "PCM Notify",
&lhandle->ctl_notify);
openctl_elem(lhandle, device, subdevice, "PCM Rate Shift 100000",
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